Process for the recovery of u in the



Jan. 3l, 1956 A. E. BALLARD PROCESS FOR THE RECOVERY OF U IN THEPRESENCE OF IRON Filed sept. 18, 1945 f raw? 75 .5in M766 Jin m46 I Erie75 a w@ Vn wwf INVENToR. @meri azierd United States Patent 'a PRCESS FORTHE RECOVERY F U THE PRESENCE 0F IRUN AlbertE. Ballard, Oak Ridge,Tenn., assignor, by mesne assignments, to the resented by the UnitedStates Atomic Energy Commission Application September 13, 1945, SerialNo. 617,126

6 Claims. (Cl. Zit-145) This invention relates to the separation andrecovery of U. More particularly,l the invention relates to the recoveryof enriched U from wash solutions or comparable liquids containing theenriched U in the presence of various extraneous materials such as asubstantial content ot' Fe.

The production or obtaining of enriched U and solutions, or liquidscontaining the U, is not ajpart of the present invention, but is thevinvention of others. Detailed disclosure is contained in a number ofcopending applications exempliied by Carter et al., Ser. No. 532,159,filed April 21, 1944, and Kamen, Ser. No. 532,160, tiled April 2l, 1944and in other copending applications to which reference may be made forfurther information relative to the production of enriched U,illustrative comn positions of the various materials obtained and otherdetails. The present invention is not limited to the treatment of anyparticular source of a liquid containing enriched U, but is particularlyapplicable to the types of solutions containing contents of Fe obtainedin processes of the type described in the aforementioned copendingapplications.

lt is sutiicient topoint out that in a number of existing processesthere results orfin connection with such processes liquids are obtainedhaving a content of valuable U therein which it is desired to recover.This U is of great value since the isotopic composition thereof asrespects certain of the isotopes may be much higher than the isotopiccomposition of natural U. As is known, natural U contains a small amountof U235, an amount of U238 approximately 139 times greater Vthan thefirst-mentioned U, together with Um, UXl and other components. By theterm enriched, or enhanced U as used herein, reference is made tomaterials in which the content of the first-mentioned isotope is largerthan in natural U whether the U be in the elemental form or in acompound, or is in some other form.

However, this valuable U in the liquids of the class aforementioned maybe in the presence of a large amount of extraneous material. While suchextraneous material may of itself have possible value, its value may beregarded as negligible as compared with the U. Hence, for the purposesof the present invention such other material may be regarded asundesirable. It happens in many instances that this extraneous materialmaybe many times greater -than the content of thevaluable U which it isdesired to recover. For example, in instances where the presentinvention is very useful, the content of the Fe in the extraneousmaterial may be many times larger than the content of U. ThatV is, asexplained in detail in the aforementioned copending applications, theliquids containing valuable U also contain extraneous materialcomprising metallic and non-metallic components such as iron, chromium,nickel, carbon, and the like. The presence of these other components maybe due to some extent to contamination in the original raw" materials,but usually extraneous material is picked up during the methods ofproducing theV enriched U, or in United States of America as rep-Y y73ans Patented Jan. 3l, 1955 the various washing methods used in suchprocesses for washing the U from stainless steel, or other parts ofisotope separation apparatus.

For example, while materials which may be treated in accordance with thepresent invention may contain from 5 to 1200 milligrams or more of U perliter, there may be present many more milligrams of iron, chromium, andnickel. Because ofthe presence of these other components which may be inhigh amounts, separation and recovery of the valuable U presents aconsiderable problem.

.I have found, as will be described in detail hereinafter, thatseparation and recovery of valuable U in the presence of 5e may beaccomplished by a procedure involving precipitating the bulk of the Fein a novel manner, separating and processing the precipitate to preventany small loss of U therein, and processing the liquid freed ing the Uin the presence of Fe to separate the U therefrom and also therebyeliminating other contaminants.

While certain of the individual steps or" my process, such as theelectrolysis step to be described, may be similar to prior procedureswhich are the inventions of others, it is believed that the combinationof steps described herein is novel. It is also believed that the stepherein of eliminating Fe as a relatively easily lterable precipitate,described as a basic iron sulfate, is novel per se, as are other aspectsof my process which will be described.

@ne object of the present invention is to provide a method for theseparation and recovery of valuable U materials particularly enhanced orenriched U.

Another object is to provide a separation and recovery method which maybe applied to liquids containing enriched U in the presence of othercomponents, particularly contents of iron and other extraneous materialand the like, whether these other components be present in relativelysmall amounts or present in quantities which exceed the quantity of thevaluable U.

Still another object is to provide a method for the separation andrecovery of enriched U from liquids containof substantial amounts of Fewhereby substantially all of the U is recovered without material loss ofthe U along with the iron.

Still another object is to provide a method for the precipitating, in anenvironment of the class described, of an easily separable ironprecipitate.

Another object is to provide a method of precipitating a basic ironsulfate in the presence of valuable U materials.

Other objects will appear hereinafter.

The composition of the liquids containing the U may vary over widelimits, and reference may be made to the aforementioned copendingapplications or companion application now Ser. No. 32,832, filed June14, 1948, for further details relative to thecomposition of suchliquids. It is suiicient for the purposes of the present description topoint out that in general the liquids which are particularly susceptibleof treatment in accordance with the present invention, in addition tocontaining the U which it is desired to recover ultimately as theperoxide also contain an undesired content of iron. This iron ifprecipitated in substantial quantities as the hydroxide often forms agumrny, sticky, nonflilterable mass which may not be completelyseparable. A certain amount of U may be lost along with such ironprecipitates. lf any great amount of iron carries through to the Uperoxide precipitation step, such iron may interfere with this step. Bythe present invention such diculties are overcome.

A general understanding of my process may be had by reference to theattached drawing forming a part of steps in accordance with oneembodiment of my invention which may be applied to liquid containing Uin the Referring now to the drawing, i represents a source of the washliquid which is to be processed containing the U and the: iron. In theusual situation this liquid isin the oxidized state because of the,presence of nitric acid. vowever, in the event that it is not in.A suchstate, it may be, oxidized by the addition of 4nitric acid and peroxideo rby other procedure."

This'oxidized wash liquid at 2 if not containing sulfate ionl may havesulfate ion incorporated by adding sulfuric acid or'sodiumacid .sulfateor other sources of sulfate ion. For example, the liquidy returned bystep 3 contains sulfate ions. Thev'olume of Vthe solution is reduced'byI concentrationftol preferablyI a 34% solutionihowever,a'more'dilutel solution such as a 1%v solution,ib`a`sed on the Ucomponent present, maybe processed but involves the handling of largerliquid volumes. Also instep 2, the pH ofy thevsolu'tion is carefullyadjusted to about 3,`5` by suitable additions. u

It hasl been found that by carefully` controlling the pH at this point,the iron present maybe precipitated in the form of ak readily'tilte'r'able material described herein as' basic ironisulfate. The exactcomposition of thisvironprecipitate is not known at present. It ispossible that the precipitate formed: under lthese conditions maycomprise a mixture of iron hydroxide and iron sulfate. In any event,however, it has been found that by precipitating thel iron. under theconditions described a readily; separable precipitate is obtained ascontrasted to the gummy, sticky and relatively non-iilterable materialwhich is obtained vif an iron hydroxide is precipitated rather than thebasic sulfate type4 of precipitate described hereinfwhich isvprecipitated by the presence of both sulfate` ions and hydroxyl ionsunder the` pH conditions described.`

It will be noted in passing that, to the liquid at 2, there may berecycled recovered liquid as indicated at 3 to supply sulfate ion. Thisaspect will be described in detail hereinafter.

The easily separable basic iron sulfate precipitate in 2 may be filteredor, centrifuged. out andl the liquid, containing U freed of its ironcontent as well as of other metallic contaminants, is conducted to step4 where it is treated with hydrogen peroxide tofprecipitate uraniumperoxide. 4By, thisy lstep the U is separated from anysmall amountsofextraneous materials such ascopper, chromium, nickel, 4and the likestilltherein so thatv the precipitate at 5 isalrelati'vely pureuraniurnperoxide` precipitate. That is, usually a substantial amount of theseother impurities such as copper, chromium and the like follow along withtheV basicL iron4 sulfate, as will be apparent,Y and are'laterseparated, This pirecipitatemay 4be further processed, as by ignition,to obtain a lower oxidewhich' may be convertedto athalide. Such lfurthertreatment of the uraniumperoxide precipi tate is merely illustrative`and isV not a limitation upon the present invention. Thenignition'of theoxide and itsconversion to the halide may bein accordance withprocedures worked out by others, suchvas by themethods described inother copending applications.

The ltrates and washings from thesteps of forming the uranium peroxideand washing the uranium peroxide precipitatefmaycontain avery smallamount of U and for completerezcovery may be conducted to salvage desaignated 9, or to the recovery step designated 76. A

'Referringfnow tolstepA 6 whereinfthe. basiciron sulfate precipitate hasbeen 4segregatedthis precipitate may ca'rry'along afsrnall amount VofvU.The ,basic iron sul-V fatey precipitate is redissolved in ay suitablefsolvent such as hydrochloric acid aslindicated under. stepv 6.l Ammoniumdiu'ranate` is. precipitated'tfromgthis; hydrochloric acid solutionY byAdmeansw of, the adtjlition-` of ammonium The filtrate from this step issubstantially free of any U, but may be conducted to the salvage step 9.All of these salvage materials 9 and 10, the latter to be describedhereinafter, may be treated by any suitable salvage operation, the exactdetails of which are not a part of the present invention and representthe work of others. For example, one salvage method is the uorinationmethod described in Smith copending application Ser. No. 596,226, tiledMay 2-8, 1945.

Considering the precipitate comprising ammonium diuranate formed in step7, this precipitate rnay be redissolved and processed to isolate theuranium therein. The isolated uranium is returned to an earlier phaseofthe process by step 3, as for example, to step 2 if it is still notpure, but usually it may be added to step 4 et seq. One method ofprocessing these solutions resulting from dissolving the ammoniumdiuranate of step 7 is by elec trolysis of a sulfuric acid solution inthe presence of a mercury cathode. The details ofl suchrelectrolyticmethodsrepresentsV the work of. others and are described in thecopending application in the name of Kamen, Ser. No. 5, 3 2 z,l6previously referred, to herein.

By suchy electrolysis any small amount of uranium which followed the Feis recovered and may be converted to an oxidized solution suitable foradding to the oxidized s olLutionL at 2. The mercury employed in theelectrolysis step may piekl up a small amount of impurities and isprocessed by distillation as indicated at 8, the residues bengentto.Salvage 1.0.,

In the above type of process itA has been found that by eliminatingv theiron content at the onset as an easily separable precipitate, thevsubsequentv precipitation and recovery ofU as the peroxide are greatlyfacilitated. As a matter of fact practically theY entire bulkof the U isrecovered at stepsv` 4 andI S. However, in, view of the substantiallyclosed system worked out, any small amount of U following the basic ironsulfate precipitate in step 6 or the various ltrates to step 9, or withthe mercury. in step 10 are recoverable and returnable to the process;hence, possibilities of anylosses in the overall process are minimized.Therefore, there can be no substantial lossy of, U in this recoveryprocess. Since the precipitation of the basic iron sulfate is relativelyrapid, there is no holdup of large quantities of the U,`but asindicated, the bulk of the U is immediately recoverable in steps 4 and5u. Any amountsofy U recovered in the steps 6, 7, 8, 9 and IOfare smalland consequently hold up of the valuable U inthese other. steps isYreduced to a minimum.

A.. further, more detailed; understanding of my invention mayy be. had by a consideration-r of.A the following examplewhich may be, regarded asappliedl to approxi. matslYfOO aellgsot lisdsntaniag U, resulting fromwashing certain stainlessu steelj partis; with a weak nitricecidolutoaand, Steam However.,- in addition'. to the content of the U whichl itwas desired to recover, the nitric acid liquid also contained asubstantial amount of iron, presumablypickedfup from the stainless steelpartsV of the isotope separation apparatus, as well as contents of.chromium, nickel and copper. The operations in this example were. asfollows: y

Ther wash liquids obtained as above indicated by scrubbing and-washingthe various apparatus parts with suitable solvents were'placed in aconventional stainless Steeljackstedtenk Thess. Solutions,whichontained, nitric artid; were. Csnenttatsd byy evaporation, t tovabout a 3%.-4% Saluti@ The Solution contained, for ex ample, U,o,2++,Feta C .r,+++. Na+ and Cu,++ ions.

A' Scalise. of; SQF- ibas. (added: as H2504); was. Sup-2 Plidtffha theRHQWaS adjusted, te 3:5: with NHtOH.

This/stessithaptecipitetign 2f-:basic .iron Sulfate TheL addition v.was; made, slowly, with stirring-and anl gramas" Then H2O2 was added tothe lltrate from the preceding step to precipitate UO4.12H2O.` The pHwas adjusted to about 2 by the addition of NHiOH after the addition ofH2O2. The resultant slurry was let stand for 15-30 minutes to promotecrystal growth and then centrifuged. The supernatant from this step wassent to salvage but contains only a very small amount of U.

The precipitate of UO4.12H2O was washed, and the washings added to thematerials for salvage. The precipitate was dried and then calcined toU03 which was used for reconversion to U chlorides. v

The precipitate of basic iron sulfate in this example contained about 1%of the U started with. The precipitate was dissolved in HC1, then the Utherein and other metals were precipitated with excess NH4OH. This Uprecipitate wasdigested, centrifuged out and washed. The filtrates andWashings were saved for salvage. This U precipitate comprised(NH4)2U2O7, Fe(OH)3, Cr(OH)3, Cu++, Ni++ and Mn++. This precipitate wasdissolved in H2804 and subjected to electrolysis, using a mercurycathode by the method of Ser. No. 532,160 aforementioned, therebyremoving substantially all impurities of Fe, Cr, Ni and Cu away fromthis U incidentally thrown down in the basic iron sulfate precipitate.The resultant solution, containing U+4, from this step was returned tothe peroxide precipitation step above described.

The dirty Hg from this step was distilled to recover pure Hg for reuse.Any residue of Fe or the like from the distillation may contain tracesof U, and was saved for salvage. All the salvage solutions from theabove steps were evaporated to dryness to hold for eventual recovery oftraces of U.

In the above example, about 99% of the U was quickly separated as theperoxide. The 1% U which was diverted along with the basic iron sulfateconstitutes a small holdup, as do the very small amounts in the salvageresidues. However, since these small amounts may be ultimatelyrecovered, the overall recovery is substantially quantitative.

in the above description certain details have been set forth forillustrating preferred conditions. That is, the use of HC1 solvent insome instances, HNO3 in other instances, and an Hg cathode have beendescribed. However, variations may be made such as using H2804 for thesolvent or other methods of electrolysis may be employed. Likewise,while concentration of the liquid to a 3% or 4% solution is preferred,1% to 8% concentra-V tion may also be used. While a pH of 3.5 ispreferred in forming the basic iron sulfate, operable results may beobtained while using higher and lower values as, for example, within therange of 3 to 3.8. It is, however, an essential part of the presentinvention that the bulk of the Fe be removed early in the process as theeasily separable basic iron sulfate, thereby giving a liquid freed of Fefrom which the greater part of the U may be easily recovered.

it is to be understood that all matters contained in the abovedescription and examples are illustrative only and do not limit thescope of this invention as it is intended to claim the invention asbroadly as possible in view of the prior ait.

I claim:

l. The process of recovering U from liquids containing U nitrate in thepresence of undesired components including at least the iron componentof the group consisting of iron, copper, chromium, and nickel compoundswhich comprises concentrating the liquid, removing at least the greaterpart of the iron component by treating the liquid with a source of asulfate ion and under controlled pH conditions of about 3.0 to 3.8whereby a precipitate of the iron is thrown down, thereafter Subjectingthe liquid freed from the bulk of the iron to treatment for recoveringthe U component, dissolving the iron precipitate, subjecting theresulting solution to electrolysis t e r for plating out the variousmetallic contaminants therein, away from the U `and returning the U fromthis step to the aforementioned U recovery step.

2. The pross of recovering U from liquidscontaining U nitrate in thepresence of extraneous components including iron which comprisesconcentrating the liquid to between l%8% with respect to the U content,r'emoving at least the bulk of the iron component by treating thesolution with a source of a sulfate ion and under controlled pHconditions of about 3.0 to 3.8, thereby causing an easily separable ironprecipitate to form, separating and dissolving the resultantprecipitate, thereafter subjecting the liquid freedvfrom the ironcomponent to treatment for recovering the 4U component by precipitation,separating the filtrate from this precipitation step and combining itwith the solution obtained by dissolving the aforementioned ironprecipitate and thereafter subjecting these liquids to treatment forrecovering any small amount of U therefrom whereby substantiallyquantitative overall recovery is accomplished.

3. The process of recovering U from liquids containing U nitrate in thepresence of undesired components including iron, copper, chromium, andnickel nitrates which comprises concentrating the solutions to between1%-8% with respect to the U content, removing the iron component bytreating the liquid with a source of a sulfate ion and under controlledpH conditions of about 3.5, separating the resultant precipitate,thereafter subjecting the filtrate from the preceding step toprecipitation treatment for recovering the U component, separating thefiltrate from this precipitation step and combining it with the solutionobtained by dissolving the aforementioned iron precipitate, subjectingthis solution to precipitation treatment with ammonia'to obtainprecipitates of iron, chromium, and other metal hydroxides, redissolvingthese precipitates in sulfuric acid, subjecting the resultant solutionto electrolysis for plating out the various metallic contaminantsincluding the iron and copper, away from the U, returning the U fromthis step to the aforementioned U precipitation and returning thesulfuric acid solution from the electrolysis step to the aforementionedprecipitation under controlled pH conditions.

4. The process of recovering U from wash solutions containing U in thepresence of components including iron, copper, chromium, and nickelwhich comprises concentrating the solutions, removing at least asubstantial amount of the iron component by treating the solution underpH conditions of about 3.5 whereby a basic iron sulfate is precipitated,separating the resultant precipitate, thereafter subjecting the ltratefrom the preceding step to precipitation treatment for throwing down theU component as a peroxide, separating the supernatant from thisprecipitation step and combining it with the solution obtained bydissolving the aforementioned iron precipitate, subjecting this solutionto precipitation treatment to obtain precipitates of any U, and anyresidual iron and chromium, redissolving these precipitates in acid,subjecting the resultant solution to electrolysis for plating out thevarious metallic contaminants including iron and chromium, away from theU, and returning the U from this step to the aforementioned Uprecipitation.

5. The process of recovering U from solutions containing U nitrate inthe presence of components including iron which comprises concentratingthe solutions, removing the iron component by treating the solution witha source of a sulfate ion and under controlled pH conditions of about3.5, separating the resultant precipitate, thereafter subjecting thefiltrate from the preceding step to precipitation treatment for throwingdown the U component, separating the supernatant freed of iron from thisprecipitation step and combining it with the solution obtained bydissolving the aforementioned iron precipitate, subjecting this solutionto precipitation treatment with ammonia to obtain another precipitate,redissolving this precipitate in sulfuric acid, subjecting the resultantsolution to electrolysis for plating outy metallic contaminantsa'wayfrom the Y'EL returning the U from; thijs step to theaforementioned' U' precipitation and returning the sulfuric acidsolution from the electrolysis step tothe aforementionedironprecipitation.

6. TheV process for the recovery of enhanced' U, from. liquidscontainingthe U in the presence of extraneous components including acontent of iron which comprises treating the liquid with sulfuric acidand adjusting the. pH to about 3.5 to throw d own atleast the bulk` ofthe iron as an easily separable basic iron sulfate precipitate whereby asupernatant liquid* freed' ofiron containing at least 95% of said1U isobtained@ immediately treating the, supernatant liquidA toprecipitate'the U',4 treating thebasic iron sulfate precipitate byprocedure including elec- V691,324 mage Jan. 14, i902. Y13405037.96Bleecker Ian. 21, 1913 2;079,60:2; Crist May 11, 1937 OTHER REFERENCESHydrogen. Ions, by' T.` Britton, D. Van Nostrand C011 N. (19291)*Qagt5275-278 and 281-283.

1. THE PROCESS OF RECOVERING U FROM LIQUIDS CONTAINING U NITRATE IN THEPRESENCE OF UNDESIRED COMPONENTS INCLUDING AT LEAST THE IRON COMPONENTOF THE GROUP CONSISTING OF IRON, COPPER, CHROMIUM, AND NICKEL COMPOUNDSWHICH COMPRISES CONCENTRATING THE LIQUID, REMOVING AT LEAST THE GREATERPART OF IRON COMPONENT BY TREATING THE LIQUID WITH A SOURCE OF A SULFATEION AND UNDER CONTROLLED PH CONDITIONS OF ABOUT 3.0 TO 3.8 WHEREBY APRECIPATED OF THE IRON IS THROWN DOWN, THEREAFTER SUBJECT ING THE LIQUIDFREED FROM THE BULK OF THE IRON TO TREATMENT FOR RECOVERING THE UCOMPONENT, DISSLOVING THE IRON PRECIPITATE, SUBJECTING THE RESULTINGSOLUTION TO ELECTROLYSIS